1. U.S. Dep’t of Justice & Federal Trade Comm’n, Horizontal Merger Guidelines § 0.1 (1992) [hereinafter Merger Guidelines], available at http://www.ftc.gov/bc/docs/horizmer.htm.
2. Id. When a group of sellers combines to exercise market power it is called oligopoly power.
3. Id.
4. E.g., In re Schering-Plough Corp., No. 9297, at 16–17 (Dec. 18, 2003) (opinion) (discussing FTC v. Indiana Fed’n of Dentists, 476 U.S. 447, 460–61 (1986), in which the Supreme Court said that “the finding of actual, sustained adverse effects on competition... is legally sufficient to supp ort a finding that the challenged restraint was unreasonable even in the absence of elaborate market analysis.”), available at http://www.ftc.gov/os/adjpro/d9297/031218commissionopinion.pdf. A number of lower court decisions have followed this principle. See, e.g., Todd v. Exxon Corp., 275 F.3d 191, 206 (2d Cir. 2001) (evidence of “an actual adverse effect on competition... arguably is more direct evidence of market power than calculations of elusive market share figures”); Toys R’ Us v. FTC, 221 F.3d 928, 937 (7th Cir. 2000) (market power can be proved “through direct evidence of anticompetitive effects”); United States v. Baker Hughes Inc., 908 F.2d 981, 992 (D.C. Cir. 1990) (“‘[m]arket share is just a way of estimating market power, which is the ultimate consideration,’ and... ‘[w]hen there are better ways to estimate market power, the court should use them’” (quoting Ball Memorial Hospital v. Mutual Hospital Insurance, 784 F.2d 1325, 1336 (7th Cir. 1986)).
5. See, e.g., FTC v. H.J. Heinz Co., 246 F.3d 708 (D.C. Cir. 2001); Merger Guidelines, supra note 1, § 0.2.